1. Field of the Invention
The present invention relates to an image forming and binding system for producing a booklet of a document file, and in particular to an image forming and binding system for producing a booklet of a document file in which images of two pages of the document file are formed on each side of a sheet conveyed in its longitudinal direction, the sheet is folded in two at its center portion in the direction the sheet is conveyed, the folded sheet is stacked one upon another, and the stacked folded sheets are then bound at the folded side edge portions thereof.
2. Discussion of the Background
A binding technology used in producing weekly magazines is well known. After both-sided printed sheets are stacked and jogged, the stacked printed sheets are stapled at their center portions in the longitudinal directions thereof by a stapling device, the stapled sheets are folded at their stapled center portions, and then the side edges of the folded sheets opposite the stapled and folded side of the folded sheets are cut off by a cutting apparatus so as to be uniform.
When the above-described binding technology is used in producing a booklet of a document file, images of four pages of the document file are formed on each printing sheet, images of two pages being formed on each side of the sheet. Further, the images of the first page (the front cover) and the last page (the rear cover) of the document file are formed on the same side of a sheet and the images of the second page and the page before the last page of the document file are formed on the backside of that sheet. Because images of four pages of the document file are formed on one sheet, when the number of total pages of the document file is a multiple number of 4, for example 8, no blank page is produced in the booklet. However, when the number of total pages of the document file is not a multiple number of 4, for example 9 in which a multiple number of 4 (i.e., 8) is added by 1, three blank pages are produced in the booklet. When the number of total pages of the document file is, for example 10 in which a multiple number of 4 (i.e., 8) is added by 2, two blank pages are produced in the booklet.
Also, a binding apparatus connected with a copying machine is known. The binding apparatus is connected with the copying machine downstream of a sheet discharging part of the copying machine in the sheet discharging direction. Sheets each carrying an image on one or both sides thereof, discharged from the copying machine, are stacked and jogged, generally without being folded, and are then stapled at edge portions at one side thereof, at the binding apparatus.
When such a system in which a binding apparatus is connected with a copying machine is used in producing a booklet of a document file, because a folding function to fold each sheet is not generally provided in the binding apparatus, an image for one page of the document file is formed on one side or both sides of a sheet by the copying machine.
In such a system in which a binding apparatus is connected with a copying machine, generally, when a previous sheet conveyed from the copying machine to the binding apparatus is jammed at the binding apparatus, the image formation for a next sheet has been already completed at the copying machine, and thereby the next sheet is also jammed at the same position where the previous sheet has been jammed at the binding apparatus, resulting in jamming of a plurality of sheets.